JP2006027162A - Image recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an image recording apparatus which can obtain good images by making a mutual shift between recording heads adjustable by an easy process. <P>SOLUTION: An inkjet printer has an ink discharge opening array aligned in a direction approximately orthogonal to a transfer direction of a recording medium, and a storage part 312 in which ink droplet striking position error data related to each discharge opening of its own is stored. The inkjet printer is equipped with a plurality of head units 31, 32, 33 and 34 constituted removably, and a head unit adjustment control part 151 which reads out the ink droplet striking position error data from the storage part 312 of the head units related to a setting when setting the head units, and which adjusts a discharge timing of ink droplets from the ink discharge openings on the basis of the read ink droplet striking position error data. The ink droplet striking position error data is composed of a first adjustment value Ki not dependent on a transfer speed of the recording medium, and a fourth adjustment value Li dependent on the transfer speed of the recording medium. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image recording apparatus including a plurality of line type recording heads.

As an image recording apparatus including a plurality of recording heads, for example, a recording head for each ink color that ejects black (Bk) cyan (C), magenta (M), and yellow (Y) ink onto a recording medium is used. There are some that perform color recording.
The recording head of such an image recording apparatus can be replaced in the event of a failure or the like.
When replacing the printheads, if the printheads are mounted in a state where the printheads are displaced relative to each other, each printhead will have an array line consisting of a plurality of ink ejection ports parallel to each other. As a result, an inclination shift between the recording heads occurs, and for example, ink droplets ejected from the respective recording heads to be recorded at the same position on the recording medium are shifted and recorded. In such a case, the color balance is lost due to the color shift, and the quality of the recorded image is significantly lowered.
In order to eliminate such misalignment between recording heads, there are measures to improve the positioning accuracy of the mounting positions of a plurality of recording heads and to adjust mechanically, and measures to electrically adjust ink ejection timing. .

As an electrical adjustment, the drive order of each block of the plurality of ink discharge ports is changed according to the inclination of the array of the plurality of ink discharge ports in each of the plurality of recording heads with respect to the scanning direction. Or an upper block, and an ink jet recording apparatus that includes a setting unit that variably sets a driving interval for each block in accordance with the magnitude of inclination is disclosed (see Patent Document 1).
JP-A-7-40551

However, since Patent Document 1 is not an adjustment for each ink discharge port, the color shift for each pixel is not eliminated. Japanese Patent Application Laid-Open No. 2004-228561 is a tilt adjustment of a recording head of a carriage type ink jet recording apparatus, and a line type ink jet recording having a recording head in which a large number of nozzles are arranged in a direction orthogonal to the conveyance direction of the recording medium. When applied to an apparatus, since the number of blocks increases, it is difficult to eliminate the deviation between the recording heads.
In the conventional mechanical adjustment, the adjustment work is difficult because the adjustment is delicate, and a long time is required for the adjustment time.

  Further, each ink discharge port for each recording head is caused by displacement of the arrangement position due to machining accuracy at the time of manufacturing the ink discharge port, displacement of the ink discharge direction, diameter of the ink discharge port, driving voltage, ink flow path resistance, and the like. Landing position deviation occurs due to the ink discharge speed. Also, in the case of a recording head composed of a plurality of head modules having a plurality of ink ejection openings, the ink droplet landing position deviation is caused by the positional deviation in the arrangement direction of the ink ejection opening arrays between the head modules due to the deviation of the head module arrangement position. Has occurred. Therefore, it is difficult to realize a high-quality image only by adjustment for each recording head.

  An object of the present invention is to realize an image recording apparatus capable of easily adjusting a shift between recording heads and obtaining a good image.

  According to a first aspect of the present invention, there is provided an ink ejection port array arranged in a direction substantially orthogonal to the conveyance direction of the recording medium, and a storage unit in which ink droplet landing position error data relating to each of the ink ejection ports is stored. A plurality of recording heads configured to be detachable, and when the recording head is mounted, the ink droplet landing position error data is read from the storage means of the recording head related to the mounting, and the read ink droplet landing position error data Control means for adjusting the ejection timing of the ink droplets from the ink ejection port based on the ink droplet landing position error data, the first landing position error amount independent of the transport speed of the recording medium, An image recording apparatus comprising: a second landing position error amount that depends on a conveyance speed of the recording medium.

  According to a second aspect of the present invention, in the image recording apparatus according to the first aspect, the first landing position error amount is a landing position of an ink droplet generated due to variation in processing between the ink discharge ports. It is characterized by an error amount.

  According to a third aspect of the present invention, in the image recording apparatus according to the first or second aspect, the recording head includes a plurality of head modules having a plurality of ink discharge ports, and the first landing position error amount is The ink droplet landing position error amount generated by the positional deviation in the arrangement direction of the ink discharge port arrays between the head modules.

  According to a fourth aspect of the present invention, in the image recording apparatus according to any one of the first to third aspects, the second landing position error amount is generated due to variations in ink discharge speeds of the ink discharge ports. It is characterized by an error amount of the landing position of the ink droplet.

  According to the first aspect of the present invention, the ink droplet landing position error data includes a component that does not depend on the recording medium transport speed (first landing position error amount) and a component that depends on the transport speed of the recording medium (second (A landing position error amount) of the recording head, the recording head having a plurality of different recording medium conveyance speeds can be accommodated, and the versatility of the recording head is enhanced. It is possible to realize an image recording apparatus capable of easily adjusting the deviation and obtaining a good image.

  According to the second aspect of the present invention, the same effects as those of the first aspect can be obtained, but also the ink droplet displacement based on the displacement of the ink discharge port and the displacement of the ink discharge direction caused by processing variations. The amount of landing position deviation can be adjusted, and an image recording apparatus capable of obtaining a good image can be realized.

  According to the third aspect of the present invention, the same effects as those of the first or second aspect can be obtained, but also the landing positions of the ink droplets based on the displacement in the arrangement direction of the ink discharge port arrays between the head modules. It is possible to realize an image recording apparatus that can adjust the amount of deviation and obtain a good image.

  According to the fourth aspect of the present invention, the same effect as in any one of the first to third aspects can be obtained, the ink discharge port driving voltage, the ink discharge port diameter, the ink flow path, and the like. Since the amount of landing position deviation of ink droplets can be adjusted based on variations in ink ejection speed caused by resistance or the like, an image recording apparatus capable of obtaining a good image can be realized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the configuration will be described.
FIG. 1 is a schematic configuration diagram of the inside of a line-type inkjet printer 1 as an image recording apparatus according to the present embodiment. As shown in FIG. 1, the ink jet printer 1 includes a paper supply unit 10, a transport unit 20, a head unit unit 30, a paper discharge unit 40, a maintenance unit (not shown) used for maintenance of the head unit unit, and the like. It is prepared for.

The paper feeding unit 10 is provided with a paper feeding tray 11 in which a plurality of recording media P1 are stacked and stored below the inside of the inkjet printer 1. A take-out device 12 is provided above one end of the paper feed tray 11 to take out the recording medium P1 on which an image is to be recorded from the paper feed tray 11 one by one.
The recording medium P1 is a variety of paper such as plain paper, recycled paper, glossy paper, OHP sheet, or a cut sheet made of various fabrics, various non-woven fabrics, resin, metal, glass, or the like. May be.

  The transport unit 20 is disposed above the paper feed unit 10 and supports the recording medium P1 to transport it in the transport direction X. The transport unit 20 includes a transport belt 21, a driving roller 22, a tension roller 23, a pressing roller 24, a transport roller 25, and a transport path 26.

  The conveying belt 21 is an annular belt that supports the recording medium P1 in a planar shape and conveys the recording medium P1 in the horizontal direction. The conveyance belt 21 is movably stretched by a driving roller 22 and a plurality of tension rollers 23. When the recording medium P1 is conveyed, the conveyance belt 21 is charged by a belt charger (not shown) to thereby be recorded on the recording medium P1. Is discharged by a static eliminator (not shown) when discharging the recording medium P1.

  The pressing roller 24 is rotatably provided as a roller that presses the conveyance belt 21 at a position where the conveyance belt 21 and the recording medium P1 start to contact each other in order to convey the recording medium P1 in a planar shape.

  The conveyance path 26 conveys the recording medium P <b> 1 supplied from the paper feed tray 11 to the conveyance belt 21, and after the recording medium P <b> 1 is conveyed along the peripheral surface of the conveyance belt 21, it is transferred from the conveyance belt to the paper discharge unit 40. It is a route to discharge. The transport rollers 25 are provided at predetermined positions on the transport path 26 as a plurality of pairs of rollers for transporting the recording medium P1 in the transport direction X of the recording medium P1.

  The head unit 30 is arranged in the vicinity of the upper portion of the transport belt 21 in order along the transport direction X with black (Bk), cyan (C), magenta (M), and yellow (Y) ink on the recording medium P1. Head units 31, 32, 33, 34 as line-type recording heads for each ink color provided with a plurality of ink ejection ports (not shown) for ejecting the transport belt 21 in a direction perpendicular to the transport direction X, respectively. It is provided over the entire width. Each head unit 31, 32, 33, 34 is arranged so that the ejection surface and the peripheral surface of the conveyor belt 21 face each other, and is detachable so that it can be replaced in the event of a failure. The recording medium P1 on which an image is formed by ejecting ink droplets from the head units 31, 32, 33, and 34 is sequentially discharged to the paper discharge unit 40.

  Each head unit 31, 32, 33, 34 extends in a direction substantially orthogonal to the conveyance direction X of the recording medium P1. In addition, each head unit 31, 32, 33, 34 has a plurality of head modules arranged in parallel in the longitudinal direction. Each head module extends in the longitudinal direction of each head unit 31, 32, 33, 34, and is staggered at a predetermined interval in the transport direction X of the recording medium P <b> 1 so that the print area for each head module partially overlaps ( It is arranged side by side in a staggered arrangement.

FIG. 2 is a partially enlarged view of the black (Bk) head unit 31.
As shown in FIG. 2, the head module 31a has an overlapping portion R in which a print area overlaps with an adjacent head module 31a in the longitudinal direction, and is staggered at a predetermined interval in the transport direction X of the recording medium P1 (staggered arrangement). ). This is because when ink droplets are ejected from all the ink ejection ports of the same row of the head module, there may be a difference in the ink ejection performance of the ink ejection ports at the end of the same row due to the influence of the fluidity of the ink, In order to reduce the recording quality of the recording medium P1, the head modules 31a are arranged in a staggered arrangement so that the ends overlap.

  In addition, four rows of ink discharge ports h of a to d are arranged on the discharge surface of the head module 31a facing the recording medium P1. In each of the columns a to d, the ink discharge ports h are arranged at a predetermined interval in a direction orthogonal to the transport direction X while being shifted in the transport direction X by a predetermined pitch in a cycle of three. The start points of each of the ink discharge port arrays a to d are arranged so as to be shifted in the direction orthogonal to the transport direction X by one pixel in the order of a, c, b, and d.

When data corresponding to the ink discharge port h of the overlapping portion R is recorded on the recording medium P1, one of the adjacent head modules is set, and ink droplets are discharged from the set ink discharge port h of the head module. ing.
For example, when 11 ink discharge ports overlap in the longitudinal direction of the head module with the number of nozzles in the overlapping portion R, the ink discharge port of one head module is the fifth or later from the end of the ink discharge port array. The ink discharge ports to be used are set in advance so that the ink discharge ports of the other head module use the sixth and subsequent ink discharge ports from the end of the ink discharge port array. Yes.

  In other words, considering the phenomenon in which the ink droplet size at the end of the head module generated due to the influence of the ink flow characteristics and the ink discharge behavior is different from the ink droplet size in the same head module row, By setting the ink discharge port to be used so as to avoid the use of the recording medium P1, the deterioration of the quality of the recorded image on the recording medium P1 is prevented.

  The paper discharge unit 40 includes a paper discharge tray 41 provided on the side of the inkjet printer 1, and the recording medium P1 on which the image is formed is sequentially discharged.

  As a maintenance unit (not shown), a typical suction operation or flushing operation can be employed as a maintenance method, and further, after the suction operation or flushing operation, waste ink droplets adhering to the ink ejection surface are excluded. It is good also as a structure provided with the mechanism which performs this wiping operation | movement.

FIG. 3 shows a control block diagram for controlling the ink jet printer 1.
As shown in FIG. 3, a CPU (Central Processing Unit) 110, a ROM (Read Only Memory) 120, a RAM (Random Access Memory) 130, an operation display unit 140, various control units 150, and the like are connected to the local bus 170. Are connected to the system bus 230 via the I / F 160. The system bus 230 is connected to a RIP (Raster Image Processor) unit 210, a host I / F 220, head units 31, 32, 33, 34, a drive circuit unit DV, and the like.

  The CPU 110 reads the system program and each processing program and data stored in the ROM 120, expands them in the RAM 130, and centrally controls the operation of the entire inkjet printer 1 according to the expanded programs. Timing control of the entire system, data storage and accumulation control using the RAM 130, data output to the head unit unit 30, input / output control of the operation display unit 140, interface (I / F) and operation control with other applications Is what you do.

  The ROM 120 stores a program and a system program for driving the inkjet printer 1, various processing programs corresponding to the system, data necessary for processing by the various processing programs, and the like. In addition, when adjusting the tilt of the head units 31, 32, 33, and 34, a reference head unit is set in advance.

  The RAM 130 is a temporary storage area for programs, input, or output data and parameters read from the ROM 120 in various processes controlled and executed by the CPU 110.

The operation display unit 140 is configured by an LCD (Liquid Crystal Display), and displays various operation buttons, device status display, operation status of each function, and the like on a display screen in accordance with an instruction of a display signal input from the CPU 110. The LCD display screen is covered with a pressure-sensitive (resistive film pressure) touch panel configured with transparent electrodes arranged in a grid, and the XY coordinates of the force point pressed with a finger or a touch pen are expressed as voltage values. The detected position signal is output to the CPU 110 as an operation signal. The operation display unit 140 includes various operation buttons such as a numeric button and a start button, and outputs an operation signal generated by the button operation to the CPU 110.
In order to realize the present embodiment, the operation display unit 140 includes a display screen and operation buttons for inputting an inclination adjustment value B described later.

The various control units 150 include a recording medium conveyance control unit that controls various rollers such as the paper supply unit 10 and the conveyance unit 20 illustrated in FIG. 1, a maintenance control unit that controls the operation of the maintenance unit, an ink supply control unit, and a waste ink control. Various control units such as a unit are provided.
In order to realize this embodiment, a head unit adjustment control unit 151 as a control means is provided.

  The RIP unit 210 converts print data (vector image data) input from a host PC or the like via the host I / F 220 into print image data (raster image data or bitmap data) according to a print instruction.

  The drive circuit unit DV drives the head modules 31a, 32a, 33a, and 34a of the head units 31, 32, 33, and 34 to discharge ink droplets from the ink discharge ports to the recording medium P1, thereby recording the recording medium P1. Print an image on top.

  Each head unit 31, 32, 33, 34 includes a head module print image plane memory for storing print image data for each head module assigned to each head module of each color head unit 31, 32, 33, 34, and And a storage unit 312 as storage means in which ink droplet landing position error data of the ink discharge port is stored.

  The ink droplet landing position error data is a first error amount that is an ink droplet landing position error that occurs depending on the machining accuracy or assembly accuracy that occurs during the manufacture of the ink discharge port h, regardless of the conveyance speed of the recording medium P1. Landing position error amount (hereinafter referred to as the first adjustment value Ki), and a second landing position error amount (which is an error amount of the landing position of the ink droplet generated by the conveyance speed and ink discharge speed of the recording medium P1). Hereinafter, it is referred to as a fourth adjustment value Li).

  The first adjustment value Ki is a variation in processing between the ink ejection ports due to machining accuracy such as drilling, water-repellent processing, water immersion processing, etc. at the time of manufacturing the ink ejection ports, and a plurality of head modules as head units. This is an error amount of the landing position of the ink droplet generated due to the positional deviation in the arrangement direction of the ink discharge port arrays between the head modules due to the assembling accuracy generated when assembling.

  The fourth adjustment value Li is an error amount of the landing position of the ink droplet generated due to variations in the ink discharge speed due to the diameter of the ink discharge port, the drive voltage, the ink flow resistance, and the like.

  The ink droplet landing position error data is separated into a component that does not depend on the recording medium conveyance speed (first adjustment value Ki) and a component that depends on the conveyance speed of the recording medium (fourth adjustment value Li). Since it is stored, it is possible to cope with an inkjet printer having a plurality of different conveyance speeds, and the versatility of the head unit 31 is enhanced.

The storage unit 312 is provided for each head unit, and ink droplet landing position error data of each ink discharge port is stored during the manufacturing process of the head unit.
As the storage unit 312, a nonvolatile storage unit such as a ROM, a DRAM (Dynamic Random Access Memory), an MRAM (Magnetoresistive Random Access Memory), or a flash memory can be used.

With the above configuration, print data input from the host PC is received by the host I / F 220 and stored in the HDD 161 or the RAM 130 connected to the I / F 160.
The print data stored in the HDD 161 or the RAM 130 is converted by the RIP unit 210 into print image data for each page of the recording medium P1 as needed. The converted print image data is divided into print image data for each color, and head module print image data assigned to each head module of the head units 31 to 34 of each color is further converted into head module print image plane memories 311, 321, 331 and 341, respectively. In order to realize the present embodiment, the CPU 110 adds a later-described fifth adjustment value Hi to the head module print image data when the head module print image data is stored. After the print image plane memory 311, 321, 331, 341 stores the head module print image data in which the fifth adjustment value Hi is added, the drive circuit unit DV replaces the head module of the corresponding head unit with the fifth adjustment value. Driving is performed based on the print image data of the head module to which Hi is added, and an image is recorded on the recording medium P1.

  Since the image is recorded according to the print image data of the head module including the fifth adjustment value Hi, the image quality due to the shift of the print line or the shift of the color due to the shift of the landing position for each ink discharge port with an easy configuration. A drop can be prevented and an ink jet printer capable of obtaining a good image can be realized.

  The head unit adjustment control unit 151 includes a CPU, a RAM, a ROM, a nonvolatile RAM, and the like, expands a program and data stored in the ROM and the nonvolatile RAM into a temporary storage area (not shown) such as a RAM, and the program. In order to realize the present embodiment based on the control, control for adjusting the ejection timing between the head units is performed, and various parts of the information in the ink jet printer 1 are connected to each other so that various information can be transmitted and received. Is received, the received information is determined, and information such as an operation instruction as a determination result is output to each unit.

  When the head units 31, 32, 33, 34 are mounted on the inkjet printer 1, the head unit adjustment control unit 151, ink drop landing positions for each ink discharge port from the recording unit of each head unit 31, 32, 33, 34. Error data (first adjustment value Ki and fourth adjustment value Li) is read and stored in the RAM or nonvolatile RAM in the head unit adjustment controller 151, and used as an adjustment print pattern for adjusting the ink ejection timing between the head units. The fifth adjustment value Hi is calculated and stored in the HDD 161 or the RAM 130. By adding the calculated fifth adjustment value Hi to the head module print image data, the ejection timing between the head units is adjusted.

  The inclination adjustment pattern is an inclination of an ink discharge port array of a head unit (hereinafter referred to as an adjustment head unit) to be adjusted with respect to an ink discharge port array of a preset head unit (hereinafter referred to as a reference head unit). This is a print pattern printed for detection and adjustment.

  The user visually observes the printed inclination adjustment pattern, and inputs an inclination adjustment value B as error information obtained by observation from the operation display unit 140 or the like.

  Specifically, the head unit adjustment control unit 151 calculates the third landing position error Ei based on the inclination adjustment value B that is determined by the user based on the print result of the inclination adjustment pattern and input from the operation display unit 140. The fifth adjustment value Hi is calculated from the third landing position error Ei and the ink droplet landing position error data (first adjustment value Ki and fourth adjustment value Li). The calculated fifth adjustment value Hi is stored in the nonvolatile RAM in the head unit adjustment control unit 151.

  The storage means for storing the fifth adjustment value Hi may be a rewritable nonvolatile storage medium, and is composed of an HDD (Hard Disk Drive), an MRAM (Magnetic Random Access Memory), a flash memory, or the like. This is not a limitation.

  The third landing position error Ei can be calculated from Equation 1 below, and the fifth adjustment value Hi can be calculated from Equation 2 below.

Ei = i / N × B (Formula 1)
i: Identification number of ink discharge port N: Total number of ink discharge ports of the head unit

  Hi = Ei + Ki + Li (Formula 2)

FIG. 4 shows an example of the relationship between the tilt adjustment pattern and the head unit.
FIG. 4 shows an example in which a magenta (M) head unit 33 is set as the reference head unit, and a yellow (Y) head unit 34 is set as the adjustment head unit.

The inclination adjustment pattern includes reference inclination lines L _S1 and L _S2 printed by ejecting ink droplets from the ink discharge ports near one end and the other end of the ink discharge port array of the head unit 33 indicated by a solid line. The adjustment inclination printed by ejecting ink droplets from the ink discharge ports near one end and the other end of the ink discharge row of the head unit 34 shown by the broken lines corresponding to the reference inclination lines L _S1 and L _S2. It consists of lines L _T1 and L _T2 .

The user visually observes the printed inclination adjustment pattern to determine the adjustment inclination lines L _T1 and L _T2 printed at the same positions as the reference inclination lines L _S1 and L _S2, and the one end side and the other end side The difference between the overlapping parts is determined as the relative inclination of the head unit to be adjusted with respect to the reference head unit, and the inclination adjustment value B is input from the operation display unit 140.

The reference inclination lines L _S1 and L _S2 are a plurality of straight lines extending in a direction Z orthogonal to the transport direction X printed at a predetermined discharge timing by a reference head unit (for example, the head unit 33). It is. At the same time as the reference inclination lines L _S1 and L _S2 are printed, the adjustment inclination lines L _T1 and L _T2 are printed.

The adjustment inclination lines L _T1 and L _T2 are discharged from a head unit (for example, the head unit 33) serving as a reference by the head unit (for example, the head unit 34) to be adjusted (hereinafter referred to as a reference discharge timing). On the other hand, a plurality of straight lines extending in the direction Z perpendicular to the transport direction X printed by changing the ejection timing every time corresponding to the unit pixel distance of the printing resolution (hereinafter referred to as unit pixel time T). It is.

Note that the lengths of the straight lines of the reference inclination lines L _S1 and L _S2 and the adjustment inclination lines L _T1 and L _T2 may be long enough to be visually recognized by the user.

In the vicinity of the adjustment inclination line L _T1 or L _T2 , it is preferable to print a numerical value or symbol indicating the change amount so that the change amount of the adjustment discharge timing with respect to the reference discharge timing can be recognized by the user.

  As a numerical value or symbol indicating the amount of change, for example, as shown in FIG. 4, “n” (n is 0 or a natural number) for indicating how many times the unit pixel time T is used. “+” Can be used in combination as a symbol indicating that the discharge timing is earlier than the timing, and “−” can be used as a symbol indicating a case where the discharge timing is later than the reference discharge timing.

In the inclination adjustment pattern shown in FIG. 4, the discharge timing at which the reference inclination line L _S1 and the adjustment inclination line LT _{1 at} one end are printed at the same position is the case where the adjustment inclination line LT ₁ is “0”. On the other hand, the discharge timing at which the reference inclination line L _S2 and the adjustment inclination line L _{T2 at} the other end are printed at the same position is when the adjustment inclination line _{LT 2} is “+1”. Therefore, by changing the ejection timing of the head unit (head unit 33) to be adjusted for each unit pixel time T, the head unit to be adjusted has one end relative to the ink ejection row of the reference head unit. It can be determined that the ink discharge port array of the head unit to be adjusted is inclined by a distance corresponding to the distance of one pixel from the first portion to the other end portion.

The user visually recognizes the numerical value or symbol indicating the amount of change printed in the vicinity of the adjustment inclination line L _T1 or L _T2 that overlaps at one end and the multi-end, and operates the operation display unit 140 as a reference. For determining the inclination of the ink discharge column of the head unit (for example, head unit 34) to be adjusted with respect to the ink discharge column of the head unit (for example, head unit 33) to adjust the inclination of the head unit to be adjusted The tilt adjustment value B is input from the operation display unit 140.
Based on the input tilt adjustment value B, the ejection timing for each ink ejection port of the head unit to be adjusted (for example, the head unit 34) is adjusted, and the tilt of the head unit is adjusted.

  In this way, the relative inclination deviation between the head units can be easily determined from the inclination adjustment pattern, and the inclination between the head units can be easily adjusted. An ink jet printer 1 that can obtain an image can be realized.

The ink color of the reference head unit is preferably a color in which the color mixture state of the ink color of the adjustment head unit is easily visually recognized when the reference head unit and the adjustment head unit print at the same position on the recording medium P1, for example Colors such as magenta (M) and cyan (C) are preferable instead of extremely dark or light colors such as black (Bk) and yellow (Y).
By setting the ink color of the reference head unit in this way, the user can easily visually recognize the determination based on the adjustment print pattern, and the user convenience is improved.

FIG. 5 shows a schematic configuration diagram of the landing position error detection device 2.
The landing position error detection device 2 shown in FIG. 5 detects the landing position error amount of each ink discharge port of the head unit in the manufacturing process of the head unit, and stores each ink discharge port in the storage unit 312 provided inside the head unit. Ink droplet landing position error data (first adjustment value Ki and fourth adjustment value Li) is stored.

The landing position error detection device 2 supports a head unit that is a target for detecting the landing position error amount, an ink absorbing medium P2 that is transported to a position facing the ink ejection surface of the head unit, and the ink absorbing medium on a plane. Transport rollers 51 and 52 for transporting in the transport direction X, and a reading unit 60 for reading the dots formed on the ink absorbing medium P2 by ejecting ink droplets from the ink ejection ports of the head unit. ing.
The landing position error detection device 2 shown in FIG. 5 shows a case where a black (Bk) head unit 31 is mounted as a head unit that is a detection target of the landing position error amount.

  The head unit 31 is provided over a direction orthogonal to the transport direction X, and is disposed such that the ink ejection surface and the surface of the ink absorbing medium P2 face each other.

  The ink absorbing medium P2 is preferably a medium in which the ink droplets ejected from the ink ejection ports do not bleed in the fiber direction and the formed dots have a uniform circular shape. For example, a medium having a fine air gap in the ink absorption layer, a high absorption speed after the ink droplets land on the ink absorption medium P2, and a spread of the ink droplets in the surface direction of the ink absorption medium P2 is suppressed. Is preferable, and void-type inkjet paper can be used.

  The reading unit 60 is a device that optically scans dots formed on the ink absorbing medium P2 and reads them as image signals by an image pickup device such as a CCD through an optical system such as a lens. In the read image signal, the contour of the dot corresponding to each ink ejection port is detected by the main control unit described later, and the median value of the detected dot contour is the dot in the virtual space corresponding to each ink ejection port. Calculated as coordinates.

FIG. 6 shows a control block diagram of the landing position error detection device 2.
As shown in FIG. 6, the main control unit 400, the reading unit 60, and the head unit 31 are connected to the system bus 471.

  The main control unit 400 includes a CPU 410, a ROM 420, a RAM 430, a transport control unit 440, various control units 450, and the like connected to the local bus 472, and is connected to the system bus 471 via the I / F 460.

  The CPU 410 reads the system program and each processing program and data stored in the ROM 420, develops them in the RAM 430, and centrally controls the operation of the entire landing position error detection device 2 according to the developed programs. It controls the timing of the entire system, the storage and accumulation control of data using the RAM 430, the operation control of the transport control unit 440 that controls the transport roller for transporting the ink absorbing medium P2, and the operation control of other various control units. is there. Further, the CPU 410 calculates the first adjustment value Ki and the fourth adjustment value Li in order to realize the present embodiment, and stores the calculated first adjustment value Ki and the fourth adjustment value Li in the storage unit 312. Give instructions to write.

  The ROM 420 stores a program and a system program for driving the landing position error detection device 2, various processing programs corresponding to the system, data necessary for processing by the various processing programs, and the like.

  The RAM 430 serves as a temporary storage area for programs, inputs, or output data and parameters read from the ROM 420 in various processes controlled and executed by the CPU 410.

  The conveyance control unit 440 is a control unit that controls the operation of conveyance mechanisms such as the conveyance rollers 51 and 52 for conveying the ink absorbing medium P2.

  The various control units 450 include various control units such as operation control units of various sensors provided in the landing position error detection device 2 and an ink supply control unit that controls supply of ink to the head unit.

As a method of calculating the first adjustment value Ki, ink droplets are ejected from a plurality of ink ejection ports of the head unit 31 while the ink absorbing medium P2 is stationary at a position corresponding to the ink ejection surface of the head unit 31. Dots are formed on the absorbing medium P <b> 2, and the formed dots are read by the reading unit 60. The image signal of a plurality of dots read from the reading unit 60 is detected as a dot outline corresponding to each ink discharge port, and the detected median value of the dot outline of each ink discharge port corresponds to each ink discharge port. Calculated as dot coordinates in the xy virtual space. The linear formula F1 is calculated by the least mean square method based on the calculated plurality of dot coordinates, and the first landing position error amount Kmi for each ink ejection port is calculated according to the calculated linear formula F1 and the plurality of dot coordinates. Ask for. Predetermined ink discharge times (hereinafter referred to as set discharge times m0) The above operation is repeated to obtain m0 first landing position error amounts Kmi for each ink discharge port, and m0 first landing position error amounts Kmi are obtained. The average value is calculated, and the calculated average value is set as the first adjustment value Ki.
Note that “m” in the first landing position error amount Kmi indicates the ink discharge times, and “i” indicates the identification number of the ink discharge port.

  Since the first adjustment value Ki calculates the landing position error amount for each ink ejection port from the dots formed in a state where the ink absorbing medium P2 is stationary, the recording medium P1 used for the mounted inkjet printer 1 is used. This shows the landing position error amount that does not depend on the transport speed.

FIG. 7 shows an example of dots formed when the ink absorbing medium P2 is stationary.
The white circles shown in FIG. 7 indicate the formed dots D, and the solid line indicates the linear formula F1 calculated by the least mean square method. A method of calculating the first landing position error amount Kmi will be described with reference to FIG. In the xy virtual space, first, the coordinates of the dot D formed for each ink ejection port are calculated, and the linear formula F1 (y = ax + b) is calculated by the least mean square method based on the calculated plurality of dot coordinates. To do. For each dot, the error amount of the x coordinate of the dot coordinate with respect to the ideal x coordinate on the calculated linear formula F1 is obtained. The obtained error amount in the x-coordinate direction is the first landing position error amount Kmi.

  For example, the first landing position error amount Kmi of the ink discharge port of ink discharge port number i is a straight line on which the dot Do should be formed from the dot coordinates (xi, yi) of the dot Di and the linear formula F1 (y = ax + b). The x coordinate (xi ′) of the ideal dot Di ′ in the equation is calculated. A difference in the x coordinate direction between the calculated ideal x coordinate (xi ′) and the x coordinate (xi) of Dodd Di is the first landing position error amount Kmi. The first landing position error amount Kmi can be calculated by the following Equation 3.

  Kmi = xi-xi '= xi-{(yi-b) / a} (Formula 3)

The fourth adjustment value Li is calculated by ejecting ink droplets from a plurality of ink ejection ports of the head unit 31 while transporting the ink absorbing medium P2 at a constant speed to form dots on the ink absorbing medium P2. The read dot 60 is read by the reading unit 60. The image signal of a plurality of dots read from the reading unit 60 is detected as a dot outline corresponding to each ink discharge port, and the detected median value of the dot outline of each ink discharge port corresponds to each ink discharge port. Calculated as dot coordinates in the xy virtual space. A linear formula F2 is calculated by the least mean square method based on the calculated plurality of dot coordinates, and the second landing position error amount Mmi for each ink ejection port is calculated according to the calculated linear formula F2 and the plurality of dot coordinates. Ask for. Predetermined ink discharge times (hereinafter referred to as set discharge times m0) The above operation is repeated to obtain m0 second landing position error amounts Mmi for each ink discharge port, and m0 second landing position error amounts Mmi. The average value is calculated, and the calculated average value is set as the second adjustment value Mi. The third adjustment value Ni is calculated by subtracting the first adjustment value Ki from the calculated second adjustment value Mi, and the fourth adjustment value Li is calculated by multiplying the third adjustment value Ni by the speed coefficient. The third adjustment value Ni and the fourth adjustment value Li can be obtained by the following expressions 4 and 5.
Note that “m” in the second landing position error amount Mmi indicates the ink discharge times, and “i” indicates the identification number of the ink discharge port.

  Ni = Ki-Mi (Formula 4)

Li = Ni × (d1 / d0) × (v1 / v0) (Formula 5)
d1: distance between the recording medium P1 and the ink ejection port in the inkjet printer 1 d0: distance between the ink absorbing medium P2 and the ink ejection port in the landing position error detection device 2 v1: conveyance of the storage medium P1 in the inkjet printer 1 Speed v0: In the landing position error detection device 2, the conveyance speed of the ink absorbing medium P2

  FIG. 8 shows an example of dots formed in a state where the ink absorbing medium P2 is conveyed at a constant speed. The white circles shown in FIG. 8 indicate the formed dots D, and the solid line indicates the linear formula F2 calculated by the least mean square method. A method of calculating the second landing position error amount Mmi will be described with reference to FIG. In the xy virtual space, first, the coordinates of the dot D formed for each ink ejection port are calculated, and the linear formula F2 (y = cx + d) is calculated by the least mean square method based on the calculated plurality of dot coordinates. To do. For each dot, an error amount of the x coordinate of the dot coordinate with respect to the ideal x coordinate on the calculated linear formula F2 is obtained. The obtained error amount in the x-coordinate direction is the second landing position error amount Mmi.

  For example, the second landing position error amount Mmi of the ink discharge port of the ink discharge port number i is a straight line on which the dot Do should be formed from the dot coordinates (xi, yi) of the dot Di and the linear formula F2 (y = cx + d). The x coordinate (xi ″) of the ideal dot Di ″ in the equation is calculated. The difference between the calculated ideal x-coordinate (xi ″) and the x-coordinate (xi) of Dodd Di is the second landing position error amount Mmi. The second landing position error amount Mmi is calculated by the following Expression 6. can do.

  Mmi = xi−xi ″ = xi − {(yi−d) / c} (Formula 6)

  The second adjustment value Mi depends on the transport speed of the ink absorbing medium P2 because the landing position error amount for each ink ejection port is calculated from the dots formed in a state where the ink absorbing medium P2 is transported at a constant speed. The landing position error amount includes an error amount to be performed and an error amount that does not depend on the conveyance speed.

  Since the third adjustment value Ni is the difference between the second adjustment value Mi and the first adjustment value Ki according to the above equation 4, the landing position error depends on the transport speed of the ink absorbing medium P2 in the landing position error detection device 2. Only quantity.

  The fourth adjustment value Li is calculated by multiplying the third adjustment value Ni by the speed coefficient of (d1 / d0) × (v1 / v0) shown in Equation 3 from Equation 5 above, so that the head unit 31 is mounted. The landing position error amount depends on the transport speed of the inkjet printer 1 to be performed.

Next, the operation of the present embodiment will be described.
9 and 10 show the operation flow of detecting ink droplet landing position error data in the present embodiment.
The main control unit 400 of the landing position error detection device 2 attaches to the landing position error detection device 2 a head unit that is the target of ink droplet landing position error data detection and writing processing in the storage unit in the head unit manufacturing process. It is determined whether or not it has been done (step S1).

  When the main control unit 400 determines that the head unit is attached to the landing position error detection device 2 (step S1; Yes), the main control unit 400 starts transporting the ink absorbing medium P2 (step S2).

  The main controller 400 determines whether or not the ink absorbing medium P2 has been transported to a position facing the ink ejection surface of the head unit (lower part of the head unit) (step S3). When the main controller 400 determines that the ink absorbing medium P2 is not transported to the lower part of the head unit (step S3; No), the transport operation is continued.

  When the main controller 400 determines that the ink absorbing medium P2 has been transported to the lower part of the head unit (step S3; Yes), the main controller 400 stops transporting the ink absorbing medium P2 (step S4).

  The main controller 400 ejects ink droplets while the ink absorbing medium P2 is stationary, and forms dots on the ink absorbing medium P2 (step S5). The main control unit 400 conveys the ink absorbing medium P2 on which dots are formed to the reading position of the reading unit 60 where the dots are read (step S6). The reading unit 60 reads the dots on the ink absorbing medium P <b> 2 and outputs the read image signal to the main control unit 400.

  The main control unit 400 calculates dot coordinates on the virtual space corresponding to each ink ejection port based on the image signal input from the reading unit 60 (step S7), and based on the calculated plurality of dot coordinates. Then, the linear formula F1 by the least square method is calculated (step S8). The main control unit 400 calculates the first landing position error amount Kmi for each ink ejection port based on the calculated dot coordinates and the linear formula F1 (step S9).

  The main controller 400 determines whether or not the ink ejection number m is equal to the set ejection number m0 (step S10). When the main control unit 400 determines that the ink ejection number m is not equal to the set ejection number m0, the main control unit 400 returns to the operation of calculating the first landing position error amount Kmi again (returns to step S2).

  The main controller 400 calculates a first adjustment value Ki that is an average value of the m0 first landing position error amounts Kmi calculated for each ink ejection port (step S11). The calculated first adjustment value Ki is temporarily stored in the RAM 430 of the main control unit 400.

  Next, the main control unit 400 starts to convey the ink absorbing medium P2 at a constant speed in order to calculate the second adjustment value Mi (step S12).

  The main controller 400 ejects ink droplets when the ink absorbing medium P2 is transported to a position facing the ink ejection surface of the head unit (lower part of the head unit), and forms dots on the ink absorbing medium P2 (step) S13).

  The main control unit 400 conveys the ink absorbing medium P2 on which the dots are formed to the reading position of the reading unit 60 where the dots are read (step S14). The reading unit 60 reads the dots on the ink absorbing medium P <b> 2 and outputs the read image signal to the main control unit 400.

  The main control unit 400 calculates the dot coordinates on the virtual space corresponding to each ink ejection port based on the image signal input from the reading unit 60 (step S15), and based on the calculated plurality of dot coordinates. Then, the linear formula F2 by the least square method is calculated (step S16). The main controller 400 calculates the second landing position error amount Mmi for each ink ejection port based on the calculated dot coordinates and the linear formula F2 (step S17).

  The main controller 400 determines whether or not the ink ejection number m is equal to the set ejection number m0 (step S18). When the main controller 400 determines that the ink ejection number m is not equal to the set ejection number m0, the main control unit 400 returns to the operation of calculating the second landing position error amount Mmi (returns to step S12).

  The main control unit 400 calculates a second adjustment value Mi that is an average value of the m0 second landing position error amounts Mmi calculated for each ink ejection port (step S19). The calculated second adjustment value Mi is temporarily stored in the RAM 430 of the main control unit 400.

  The main control unit 400 calculates a third adjustment value Ni by subtracting the first adjustment value Ki from the second adjustment value Mi temporarily stored in the RAM 430 for each ink ejection port (step S20). The calculated third adjustment value Ni is temporarily stored in the RAM 430.

  The main control unit 400 calculates the fourth adjustment value Li by multiplying the third adjustment value Ni temporarily stored in the RAM 430 by the speed coefficient for each ink ejection port (step S21). The calculated fourth adjustment value Li is temporarily stored in the RAM 430.

  The main control unit 400 writes the first adjustment value Ki and the fourth adjustment value Li stored in the RAM 430 in the storage unit of the head unit (step S22).

  In this way, a head unit in which the first adjustment value Ki and the fourth adjustment value Li are stored in the storage unit is manufactured.

FIG. 11 shows an operation flow for adjusting the discharge timing in the present embodiment.
The head unit adjustment control unit 151 of the ink jet printer 1 determines whether or not all the head units that can be attached to and detached from the ink jet printer 1 have been attached (step S31).

  The head unit adjustment control unit 151 reads the first adjustment value Ki and the fourth adjustment value Li from the storage unit of each head unit, and temporarily stores them in the RAM or the nonvolatile RAM in the head unit adjustment control unit 151 (step S32). ).

  The head unit adjustment control unit 151 sets the reference head unit in order to adjust the inclination of the ink discharge port array of the adjustment head unit with respect to the ink discharge port array of the reference head unit (step S33).

  The head unit adjustment control unit 151 selects and sets the adjustment head unit after setting the reference head unit (step S34).

  After the head unit adjustment control unit 151 sets the adjustment head unit, the recording medium P1 starts to be conveyed at a constant speed (step S35).

  When the recording medium P1 is conveyed at a constant speed, the head unit adjustment control unit 151 performs a tilt adjustment pattern printing process in cooperation with various control units (step S36). After the tilt adjustment pattern is printed on the recording medium P1, the conveyance of the recording medium P1 is stopped (step S37).

  The user visually observes the inclination adjustment pattern printed on the storage medium P1, determines the inclination of the ink discharge port array of the adjustment head unit with respect to the ink discharge port array of the reference head unit, and operates the operation display unit 140. To input the tilt adjustment value B. (Step S38). The input tilt adjustment value B is temporarily stored in the RAM or nonvolatile RAM in the head unit adjustment control unit 151.

  The head unit adjustment control unit 151 calculates the third landing position error amount Ei of each ink discharge port based on the inclination adjustment value B temporarily stored in the RAM or the nonvolatile RAM in the head unit adjustment control unit 151. (Step S39), the calculated third landing position error amount Ei is temporarily stored in the RAM or the nonvolatile RAM in the head unit adjustment control unit 151.

  The head unit adjustment control unit 151 is based on the third landing position error amount Ei, the first adjustment value Ki, and the fourth adjustment value Li temporarily stored in the RAM or the nonvolatile RAM in the head unit adjustment control unit 151. A fifth adjustment value Hi for each ink ejection port is calculated (step S40).

  The head unit adjustment control unit 151 stores the calculated fifth adjustment value Hi in the HDD 161 or the RAM 130 (step S41).

  After storing the fifth adjustment value Hi, the head unit adjustment control unit 151 determines whether there is an unadjusted head unit for which the fifth adjustment value Hi has not been calculated (step S42). When there is an unadjusted head unit (step S42; No), the head unit adjustment control unit 151 adjusts the inclination of the unadjusted head unit (returns to step S34).

  If the head unit adjustment control unit 151 determines that there is no unadjusted head unit (step S42; Yes), the head unit adjustment control unit 151 ends the tilt adjustment operation of the head unit.

  As described above, each head unit 31, 32, 33, 34 includes a storage unit that stores ink droplet landing position error data for each ink discharge port, and the head units 31, 32, 33, 34 are attached to the inkjet printer 1. If the ink droplet landing position error data is read from the storage unit, the inclination adjustment pattern is printed, and the ink ejection timing is adjusted based on the inclination adjustment pattern result (tilt adjustment value B) and the ink droplet landing position error data. By providing the head unit adjustment control unit 151 that performs the adjustment, it is possible to adjust the mutual displacement between the head units by an easy process, and it is possible to realize the ink jet printer 1 that can obtain a good image without color displacement.

  Also, deviations in the positions of the ink discharge ports, deviations in the ink discharge direction, positional deviations in the arrangement direction of the ink discharge port arrays between the head modules, ink discharge port diameters, drive voltages, ink flow paths, and the like. An ink droplet landing position error amount based on variations in ink discharge speed caused by resistance or the like can be adjusted, and an image recording apparatus capable of obtaining a good image can be realized.

  Further, the present invention is not limited to the contents of the above embodiment, and can be appropriately changed without departing from the gist of the present invention.

It is a schematic block diagram inside the inkjet printer 1 in this Embodiment. 4 is a partially enlarged view of a black (Bk) head unit 31. FIG. 2 is a control block diagram for controlling the ink jet printer 1. FIG. It is an example of the relationship between an inclination adjustment pattern and a head unit. 2 is a schematic configuration diagram of a landing position error detection device 2. FIG. 3 is a control block diagram of a landing position error detection device 2. FIG. It is an example of a dot formed in a state where the ink absorbing medium P2 is stationary. It is an example of dots formed in a state where the ink absorbing medium P2 is conveyed at a constant speed. It is a detection operation | movement flow of the ink droplet landing position error data in this Embodiment. FIG. 12 is an operation flow of detecting ink droplet landing position error data in the present embodiment (continuation of FIG. 11). It is a discharge timing adjustment operation flow in the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Landing position error detection apparatus 10 Paper feed part 11 Paper feed tray 12 Extraction apparatus 20 Conveyance part 21 Conveyance belt 22 Drive roller 23 Tension roller 24 Press roller 25 Conveyance roller 26 Conveyance path 30 Head unit parts 31 and 32 33, 34 Head unit portion 31a Head module 40 Paper discharge portion 41 Paper discharge tray 51, 52 Transport roller 60 Reading portion 110 CPU
120 ROM
130 RAM
140 Operation Display Unit 150 Various Control Units 151 Head Unit Adjustment Control Unit 160 I / F
161 HDD
170 Local bus 210 RIP unit 220 Host I / F
230 System Bus 311 Head Module Print Image Plane Memory 312 Storage Unit 400 Main Control Unit 410 CPU
420 ROM
430 RAM
440 Transport control unit 450 Various control units 460 I / F
471 System bus 472 Local bus B Inclination adjustment value D Dot DV Drive circuit unit Ei Third landing position error amount F1, F2 Linear equation h Ink discharge port Hi Fifth adjustment value Ki First adjustment value Kmi First landing position error amount Mi Second adjustment value Mmi Second landing position error amount Ni Third adjustment value L _S1 , L _S2 Reference inclination line L _T1 , L _T2 Adjustment inclination line Li Fourth adjustment value P Recording medium P2 Ink absorbing medium R Overlapping portion X Transport direction x x coordinate direction in virtual space y y coordinate direction in virtual space Z direction orthogonal to transport direction

Claims (4)

An ink discharge port array arranged in a direction substantially orthogonal to the recording medium conveyance direction and a storage unit storing ink droplet landing position error data relating to each ink discharge port of the recording medium are configured to be detachable. A plurality of recording heads;
When the recording head is mounted, the ink droplet landing position error data is read from the storage means of the recording head associated with the mounting, and the ink droplet discharge timing from the ink discharge port is adjusted based on the read ink droplet landing position error data Control means to
With
The ink droplet landing position error data is
A first landing position error amount independent of the conveyance speed of the recording medium;
A second landing position error amount depending on the conveyance speed of the recording medium;
Consisting of,
An image recording apparatus. The image recording apparatus according to claim 1,
The first landing position error amount is:
An error amount of the landing position of the ink droplet generated due to variations in processing between the ink discharge ports,
An image recording apparatus. The image recording apparatus according to claim 1 or 2,
The recording head comprises a plurality of head modules having a plurality of ink ejection openings,
The first landing position error amount is:
An error amount of the landing position of the ink droplet generated due to the positional deviation in the arrangement direction of the ink discharge port arrays between the head modules;
An image recording apparatus. In the image recording device according to any one of claims 1 to 3,
The second landing position error amount is
An error amount of the landing position of the ink droplet generated due to variations in the ink discharge speed of the ink discharge port;
An image recording apparatus.

Images